WO2008007564A1 - Inkjet application device, multi-layered information recording medium, and method of producing the medium - Google Patents

Abstract

An inkjet application device for applying a radiation curing resin to a target application object while moving either the object or an inkjet head relative to the other. The inkjet application device has the inkjet head and a drive section for moving the inkjet head relative to the target application object. The inkjet head has an inkjet unit having an inkjet nozzle for discharging liquid drops of the radiation curing resin, and also has a radiation application unit provided at a position spaced from and rearward of the inkjet unit relative to the direction of that movement of the inkjet unit that is provided relative to the target application object. The radiation application unit applies radiation to the liquid drops of the radiation curing resin applied to the target application object.

Description

 Specification

 Ink jet coating apparatus, multilayer information recording medium, and method of manufacturing the same

 The present invention relates to an information recording medium intended for reproduction or recording / reproduction, and a method of manufacturing the same. In particular, the present invention relates to a multilayer information recording medium having an information recording layer of two or more layers and a method of manufacturing the same.

 Background art

 In recent years, research on optical information recording methods has been advanced, and has become widely used in industrial and consumer applications. In particular, optical information recording media capable of recording information at high density such as CDs and DVDs are in widespread use. Such an optical information recording medium is capable of recording metal thin films and heat on a transparent substrate on which pits representing information signals and concave and convex shape signals such as guide grooves for tracking recording / reproducing light are formed. Thin film materials and the like are laminated, and a protective layer is further laminated. The protective layer is composed of a resin layer, a transparent substrate or the like which protects the metal thin film, thin film material and the like by force and moisture in the air. Information is reproduced by irradiating a laser beam to the metal thin film or thin film material and detecting a change in the amount of reflected light.

 [0003] In the case of a CD, a metal thin film or thin film material is laminated on a resin substrate having a thickness of about 1.1 mm having an uneven shape indicating an information signal on one side, and then coated with an ultraviolet curing resin or the like. It is produced by forming a protective layer. Note that the reproduction of the information signal is performed by entering the laser light from the substrate side, not the protective layer side.

In the case of a DVD, after laminating a metal thin film or thin film material on an uneven surface on a resin substrate having a thickness of about 0.6 mm, UV curing of the separately prepared resin substrate having a thickness of about 0.6 mm is performed. It is manufactured by pasting together with resin etc. In the case of optical information recording media, the demand for large capacity is increasing, and in DVD and the like, multi-layered information layers are achieved, and a signal layer formed of a concavo-convex shape signal and a metal thin film or thin film material is thick. An optical information recording medium with a two-layer structure is proposed, which is composed of an intermediate layer of several tens of meters. In recent years, with the spread of digital high-definition broadcasts, next-generation optical information recording media having higher density and larger capacity than DVDs are required. For example, a large-capacity recording medium such as a Blu-ray disc has been proposed, in which a metal thin film or the like is laminated on an uneven surface on a substrate having a thickness of 1.1 mm, and a protective layer having a thickness of about 0.1 mm is further formed. In the case of Blu-ray Disc, the track pitch of the information layer formed in a concavo-convex shape is narrower than that of the DVD, and the pit size is smaller. Therefore, it is necessary to narrow the spot of the laser for recording and reproducing information on the information layer. The Blu-ray Disc uses a blue-violet laser with a short wavelength of 405 nm as the laser light, and uses an optical head with a 0.85 numerical aperture (NA) as an objective lens to narrow the laser light. . The optical head narrows down the spot of the laser light on the information layer. However, as the spot becomes smaller, it becomes more susceptible to the tilt of the disk, and even a slight tilt of the disk causes aberrations in the beam spot. When an aberration occurs in the beam spot, a problem occurs that distortion occurs in the narrowed beam and recording and reproduction become impossible. Therefore, with Blu-ray discs, the defect is overcome by making the thickness of the protective layer on the laser incident side of the disc as thin as 0.1 mm.

 [0006] Incidentally, also in the next-generation optical information recording medium of large capacity such as this Blu-ray disc, a large capacity capacity of storage capacity is proposed by multi-layering of the information layer as well as DVD.

 FIG. 2 is a cross-sectional view of a two-layered Blu-ray disc having two information recording layers.

This two-layer Blu-ray disc has a metal thin film on the molded resin substrate 201 with the first information surface 202 formed on its one side by a concavo-convex shape, and a thin film material that can be thermally recorded. The first information recording layer 203 is formed. A resin intermediate layer 204 substantially transparent to recording and reproducing light is formed on the first information recording layer 203, and a second information surface 205 having a concavo-convex shape is formed on the resin intermediate layer 204. ing. A second information recording layer 206 is formed on the second information surface 205 by laminating a metal thin film having transmissivity for recording and reproducing light or a thin film material capable of thermal recording. A protective layer 207 coated with a resin substantially transparent to recording and reproduction light is provided to cover the second information recording layer 206. In this two-layer Blu-ray disc, a laser beam is made incident from the protective layer 207 side to focus on the information recording layer to be recorded or reproduced among the first information recording layer or the second information recording layer. By Signal recording and reproduction can be performed. The thickness of the molded resin substrate 201 is about 1.1 mm, the thickness of the resin intermediate layer is set to about 25 m, and the thickness of the protective layer 207 is set to about 75 μm.

The term “substantially transparent” as used herein means having a transmittance of about 90% or more to the recording and reproducing light, and “translucent” refers to 10% to the recording and reproducing light. It means having a transmittance of 90% or less!

[0009] A method of manufacturing such a multilayer Blu-ray disc is generally performed as follows. As an example, a method of manufacturing a two-layer Blu-ray disc will be described.

First, a molded resin substrate is prepared. The molded resin substrate is molded by a resin molding method such as an injection molding method using a metal stamper. As a substrate material, materials such as polycarbonate having excellent formability are often used. After that, the resin layer is laminated by using a step of forming a resin layer using a spin coating method as shown in Patent Document 1 or the like.

FIGS. 4 (a) to 4 (i) are diagrams showing a process of producing a two-layer disc including a process of producing a resin intermediate layer and a protective layer using a spin coating method.

 (a) A molded resin substrate 401 having a thickness of about 1.1 mm is formed by a resin molding method such as an injection molding method using a metal stamper. The molded resin substrate 401 has a first information surface which is formed by a pit and a guide groove which also has an uneven shape force on one side.

 (b) Next, a first information recording layer 402 is formed by forming a thin metal film or a thin film material capable of thermal recording on the first information surface described above by a sputtering method, an evaporation method, or the like. .

(c) The molded resin substrate 401 on which the first information recording layer is formed is fixed on the rotary stage 403 by a method such as vacuum adsorption (FIG. 4 (a)).

 (d) A radiation curable resin A 404 is concentrically applied on the desired radius to the first information recording layer 402 on the molded resin substrate 401 fixed to the rotary stage 403 (FIG. 4). (b)).

(e) Thereafter, the radiation curable resin A404 is stretched by spin-rotating the rotary stage 403 to form the resin layer 406 (FIG. 4 (c)). At this time, the thickness of the resin layer 406 is arbitrarily set to the viscosity of the radiation curable resin A 404, the number of rotations of spin rotation, the rotation time, and the ambient atmosphere under which the spin is rotated, such as temperature and humidity. By doing Can be controlled to a desired thickness.

 (f) After stopping the spin rotation, the resin layer 406 is hardened by the irradiation of the irradiation device 405.

 Next, the resin layer 411 is formed on the transfer stamper 407.

 (a) A transfer stamper 407 for forming a second information surface is formed by injection molding using a metal stamper.

 (b) The transfer stamper 407 is fixed on the rotary stage 408 by vacuum suction or the like.

(c) A radiation curable resin B 409 is concentrically applied on the desired radius on the transfer stanno 407 fixed to the rotary stage 408 by a dispenser (FIG. 4 (d)).

 (d) Next, the radiation curable resin B409 is stretched by spin-rotating the rotary stage 408 to form the resin layer 411 (FIG. 4 (e)). The thickness of the resin layer 411 can be controlled to the desired thickness as described above.

 (e) After stopping the spin rotation, the resin layer 411 is cured by irradiation with radiation from the radiation irradiator 410.

 Next, the resin layer 411 having the second information surface is transferred from the transfer stamper 407 onto the molded resin substrate 401.

 (a) The cured resin substrate 401 on which the resin layers 406 and 411 are respectively formed and the transfer stamper 407 are radiation hardened so that the resin layers 405 and 411 face each other on the rotary stage 413. The oil is superimposed via C412 (Fig. 4 (f)).

 (b) Next, the radiation curable resin C is stretched and controlled to a desired thickness by spin-rotating the rotary stage 413 in a state where the molded resin substrate 401 and the transfer stamper 407 are integrated. A resin layer 414 is formed.

 (c) Next, radiation is applied by the radiation irradiator 415 to cure the radiation curable resin C412 (FIG. 4 (g)). The molded resin substrate 401 and the transfer stamper 407 are integrated by the radiation curable resin C412.

(d) Thereafter, the transfer stamper 407 is peeled off at the interface between the transfer stamper 407 and the radiation curable resin B411. Thereby, the second information surface is formed on the molded resin substrate 401 (FIG. 4 (h)). (e) A second information recording layer 416 is formed on the second information surface by depositing a metal thin film, a thin film material capable of thermal recording, or the like by a sputtering method, an evaporation method, or the like.

 (f) Thereafter, a radiation curable resin D is applied by the same spin coating method, and a protective layer 417 is formed by radiation curing (FIG. 4 (i)). In some cases, a hard coat layer or the like may be formed on the protective layer to prevent defects on the surface of the protective layer due to adhesion of scratches or fingerprints.

 In this way, a two-layer Blu-ray disc is completed.

 The radiation curable resin A 404 used herein is made of a material having good adhesion to the first information recording layer 402 and the radiation curable resin C 414. The radiation curable resin B411 has good releasability from the transfer stamper 407 and good adhesion to the radiation curable resin C414. Further, these radiation curable resins A, B, C and D use those substantially transparent to the wavelength of the recording / reproducing light. In addition, although the process of preparing the resin intermediate layer using three types of radiation curable resin was described here, the releasability from the radiation curable resin and the like were selected by the selection of the material of the transfer stopper. There is also a simpler method of reducing the types of radiation curable resins by control.

 [0015] Further, as a method for forming a resin layer, a method by screen printing or the like which is not the only method by the spin coating method shown here has been proposed. In this method, the partial force of the formation of the radiation curable resin layer is the same as the screen printing method, except for the S spin coating method.

 Patent Document 1: Japanese Patent Application Laid-Open No. 2002-092969

 Disclosure of the invention

 Problem that invention tries to solve

However, when the resin intermediate layer is formed by spin coating, the resin supply may be performed only in a specific region. In addition, the centrifugal force used for drawing differs depending on the radial position. Due to these factors, there is a problem that it is difficult to form a radiation curable resin layer with a uniform thickness. Further, since the resin reaches the outer peripheral end face of the molded resin substrate, there is a problem that the resin layer is raised at the outermost peripheral part under the influence of the surface tension of the end face. Furthermore, the spin coating method is susceptible to the unevenness of the surface to be coated. example For example, when manufacturing a multilayer information recording medium having an information recording layer of three or four layers, or when forming a protective layer, spin coating is performed on a previously formed resin intermediate layer. In this case, since the influence of the unevenness of the resin intermediate layer of a plurality of layers is accumulated, the thickness uniformity may be further deteriorated.

In addition, when using a spin coating method, it takes about 10 seconds to apply a radiation curable resin once, which is a factor to reduce the production efficiency in the production of a multilayer information recording medium. It is also getting worse. In the case of spin coating, since the resin layer is formed while shaking off a portion of the resin dropped on the substrate, the amount of resin necessary for the resin intermediate layer actually formed on the substrate is larger than that of the resin layer. Needs to be dripped. Furthermore, it is necessary to reuse the resin that has been shaken off from above the substrate through a new process such as the ability to be discarded as it is or recycling. The treatment of this shaken off grease is also a factor that causes a decrease in productivity.

 [0019] In the step of forming a resin intermediate layer by screen printing, it is easier to realize a uniform thickness as compared to spin coating. On the other hand, in the screen printing method, the screen contacts the information recording layer, the information surface of the transfer stamper, etc. at the time of coating, and therefore, the information recording layer may generate scratches or dust directly or indirectly. And there are some issues. Further, in the case of the screen printing method, since the force resin is supplied only to the hole portion opened in the screen, there is a problem that air bubbles are easily collected in the portion where the resin is not supplied. Furthermore, even in the case of the screen printing method, in order to apply the resin to the desired area, it is necessary to mask so as to block the portion other than the desired application area, and the mechanical position with respect to the application surface is required. It is also necessary to match the accuracy etc with high accuracy. Also in the screen printing method, as in the spin coating method, it is necessary to supply more resin than necessary to the resin intermediate layer actually formed on the substrate. It is necessary to recycle unused resin through a new process such as disposal or recycling. The treatment of this useless resin also causes a decrease in productivity.

[0020] As a means for solving the problems associated with spin coating and screen printing, it is possible to apply a non-contact coating by an ink jet method without requiring a special mask or the like in a desired coating area. A construction method can be considered. The inkjet method is a technology for ejecting minute droplets of a volume lpL to a degree of about InL, and a nozzle used for the ejection is called an inkjet nozzle. There are various methods for discharging the resin 1S What is common is that the viscosity of the discharge liquid can only be discharged with a low viscosity because of the structure of discharging the small diameter ink jet nozzle force and the small droplet. Here, that the viscosity of the discharge liquid is low means that the viscosity of the resin in the vicinity of the discharge outlet of the ink jet nozzle is lower than the viscosity of the discharge liquid in the liquid tank at normal temperature. That is, in the ink jet method, it is necessary to lower the viscosity of the resin around the discharge port. For example, a method may be used in which the vicinity of the discharge port of the ink jet nozzle is heated by a heater or the like to reduce the viscosity of the discharge liquid and discharge it. At present, in the ink jet nozzle generally used or sold, the viscosity in the vicinity of the discharge port of the dischargeable discharge liquid is about several mPa's to several tens of mPa's.

 In the case of producing a resin intermediate layer using an ink jet method, since a low viscosity resin is discharged from an ink jet nozzle, the flow of resin tends to occur after application. Therefore, there are problems such as swelling of the resin occurring on the end face of the application area, or resin overflowing more widely than the desired application area. Further, as described above, since only minute droplets of about lnL can be discharged from the volume lpL, there arises a problem that it is very difficult to apply a thickness exceeding 10 / z m, for example.

 An object of the present invention is to solve the above-mentioned problems in the ink jet method, and for example, a resin intermediate layer having a uniform thickness is produced even in a thickness exceeding 10 μm, and a multilayer having good signal characteristics is provided. A method of manufacturing an information recording medium is provided.

 Means to solve the problem

In the present invention, the problems in the above-mentioned ink jet method can be solved by the following means. That is, the inkjet coating apparatus according to the present invention is an inkjet coating apparatus that applies a radiation curable resin to the application target while relatively moving either one of the application target or the inkjet head. ,

An ink jet unit having an ink jet nozzle for discharging droplets of a radiation curable resin, and a back side of the relative movement direction of the ink jet unit with respect to the application object is provided spaced apart by a predetermined distance, and is applied to the application object Said radiation curing The ink jet head comprises a radiation irradiation unit for irradiating the resin with radiation, and a drive unit for moving the ink jet head relative to the object to be coated.

 By using the above-mentioned configuration, it becomes possible to perform radiation curing sequentially after coating while applying a low viscosity radiation curable resin with an ink jet nozzle, and the flow of the low viscosity radiation curable resin. Can be suppressed.

 Further, the drive unit may move the ink jet head relative to the application target at a constant speed. In this case, the radiation curable resin applied to the object to be applied such as the ink jet nozzle can be irradiated with radiation sequentially after a predetermined time after application. Furthermore, the drive unit may move the ink jet head relative to the application object in a linear direction.

 Furthermore, the inkjet head is held between the inkjet nozzle unit and the radiation irradiation unit.

 A radiation shielding plate may be further provided to prevent irradiation of the radiation irradiated from the radiation irradiation unit before the droplets of the radiation curable resin discharged from the ink jet nozzle are applied.

Further, the ink jet head includes a first radiation irradiating unit and a second radiation irradiating unit disposed at a predetermined distance from the ink jet unit at the front and the rear of the relative moving direction with the ink jet unit interposed therebetween. And a radiation irradiation unit.

Furthermore, the driving unit causes the inkjet head to reciprocate in a linear direction relative to the application object, and to relatively move the inkjet head.

 When reversing the relative movement direction, the inkjet head switches from the first radiation application unit to the second radiation application unit to apply radiation.

Furthermore, in the ink jet heater, a plurality of ink jet nozzles are arranged in the ink jet nozzle unit in a direction perpendicular to the relative movement direction and over the width of the object to be coated, Well. By using this configuration, efficient radiation curable resin can be applied.

 A method of manufacturing a multilayer information recording medium according to the present invention comprises a substrate, a plurality of information recording layers disposed on the substrate, and a resin intermediate layer disposed between the information recording layers. A method for producing a multilayer information recording medium having a protective layer provided on the information recording layer, the method comprising: an inkjet unit having an inkjet nozzle for discharging droplets of a radiation curable resin; An ink-jetting unit provided at the back of the relative movement direction of the ink-jet unit spaced apart by a predetermined distance and irradiating the radiation-curable resin applied to the application object with radiation A radiation curable resin is dropped from the ink jet unit onto the object to be coated using an ink jet coating apparatus having a head and moved relative to the object to be coated. And then, by irradiating radiation to the radiation-curable 榭脂 from sequentially radiation irradiation unit, the object to be coated radiation curable 榭脂 the coating and irradiation steps of forming a 榭脂 intermediate layer on the

 It is characterized by including.

 The above configuration enables formation of a resin intermediate layer having a uniform thickness.

 Further, the object to be coated in the coating and irradiation steps may be a substrate provided with an information recording layer. In this case, the method may further include a transfer step of forming an information surface on the surface of the radiation curable resin formed on the substrate by transfer.

 Furthermore, the application target in the application and irradiation steps may be a transfer stamper. In this case, an overlapping step of sandwiching the radiation curable resin and overlapping the transfer stamper and the substrate;

 And a peeling step of peeling the transfer stamper from the radiation curable resin.

 Further, in the application and irradiation steps,

 A radiation curable resin is dropped onto the radially inner inner edge and the radially outer outer edge, and the radiation curable resin is then irradiated with radiation to have a predetermined coating thickness. Forming wall surfaces of an inner edge portion and an outer edge portion surrounding a region forming the resin intermediate layer made of resin;

A radiation curable resin is applied to the area surrounded by the wall surface of the inner edge and the outer edge. After dripping, irradiating the radiation curable resin with radiation to form a resin intermediate layer;

 May be included.

 According to the above configuration, the radiation curable resin is applied to the area surrounded by the inner edge and the wall of the outer edge, so that a resin intermediate layer having a uniform thickness is realized even if the resin has fluidity. it can.

 Furthermore, in the coating and irradiation steps, the ink jet coating apparatus is moved relative to the object to be coated at a constant speed, and a predetermined time has elapsed since the radiation curable resin is applied. It may be irradiated later.

Furthermore, a plurality of the application and irradiation steps may be performed.

 In addition, the irradiation dose of the radiation in the last step of the plurality of application and irradiation steps may be smaller than the irradiation dose in the previous application and irradiation steps. Furthermore, in the last step of the plurality of application and irradiation steps, only the radiation curable resin may be applied.

 According to the above configuration, the outermost surface of the radiation curable resin has an uncured portion, so that good information transfer can be realized.

Further, in the application and irradiation steps, a plurality of types of resins may be used as the radiation curable resin. With this configuration, it is possible to form a resin intermediate layer in which a plurality of resins having different functions are laminated.

 Furthermore, a multilayer information recording medium according to the present invention is manufactured using the method for manufacturing the multilayer information recording medium. Furthermore, this multi-layer information recording medium is characterized in that the end face of the resin intermediate layer exhibits a zigzag shape by the droplets from the ink jet nozzle. The end face has a zigzag shape by the ink jet method.

 Effect of the invention

 [0038] According to the present invention, the inkjet nozzle unit has an inkjet nozzle unit having an inkjet nozzle force, and a radiation irradiating unit, wherein the radiation irradiating unit scans the object to be coated relatively. Provided in the latter stage,

While applying low viscosity radiation curable resin with ink jet nozzle, It becomes possible to perform radiation curing, suppress the flow of a low viscosity radiation curable resin, and form a resin intermediate layer of uniform thickness.

 Brief description of the drawings

 FIG. 1 is a schematic view showing the configuration of an inkjet coating apparatus according to Embodiment 1 of the present invention. FIG. 1 is a view showing an example of a coating and irradiation process using the ink jet coating apparatus. is there.

 FIG. 2 is a cross-sectional view showing the configuration of a two-layer Blu-ray disc.

 [FIG. 3] (a) to (f) are diagrams showing steps of producing a metal stamper.

 [FIG. 4] (a) to (i) are diagrams showing a process of producing a two-layer disc including a process of producing a resin intermediate layer and a protective layer using a spin coating method.

 [FIG. 5] (a) and (b) are cross-sectional views showing a typical configuration example of the ink jet nozzle.

 FIG. 6 is a cross-sectional view showing a structure of a multilayer information recording medium in accordance with Embodiment 1 of the present invention.

 [FIG. 7] (a) to (c) are diagrams showing configuration examples of the ink jet nozzle unit.

 FIG. 8 is a view showing the configuration of an ink jet nozzle unit according to Embodiment 1 of the present invention.

 [FIG. 9] (a) and (b) are diagrams showing a plurality of application and irradiation steps in the first embodiment of the present invention.

 [FIG. 10] (a) to (d) are diagrams showing an example of a process of transferring an information surface to a resin intermediate layer according to Embodiment 1 of the present invention.

 [FIG. 11] (a) and (b) are diagrams showing the relationship between a molded resin substrate and an ink jet nozzle unit.

 [FIG. 12] (a) to (c) are diagrams showing an example of a coating and an irradiation process using the ink jet coating apparatus according to Embodiment 2 of the present invention.

 Explanation of sign

[0040] 101 molded resin substrate

 102 1st information recording layer

 103 stages

104 Ink jet nozzle unit 105 radiation shield

 106 Radiation means

 107 Inkjet head

 108 Microfluidization

 109 Radiation curable resin

 110 Cured Radiation Hardening Moonlight 1

201 Molded resin substrate

 202 First Information Plane

 203 First information recording layer

 204 resin interlayer

 205 Second Information Plane

 206 Second information recording layer

 207 Protective layer

 301 Master

 302 Photosensitive film

 303 Exposure beam

 304 Exposure unit

 305 Uneven pattern

 306 Recording Master

 307 Conductive thin film

 308 Metal plate

 309 Transfer stamper

 401 Molded resin substrate

 402 First information recording layer

 403 rotation stage

 404 Radiation curable resin A

 405 Irradiator

406 Resin layer 407 Transfer stamper

 408 rotation stage

 409 Radiation curable resin B

410 Irradiator

 411 resin layer

 412 Radiation curable resin C

413 rotary stage

 414 resin layer

 415 Irradiator

 416 Second information recording layer

 417 protective layer

 501 discharge liquid

 502 Vibration element

 503 heater

 504 Ejection fluid

 601 Molded resin substrate

 602 First information recording layer

 603 First Resin Intermediate Layer

 604 Second information recording layer

 605 Second resin interlayer

 606 Third information recording layer

 607 Third resin interlayer

 608 Fourth Information Recording Layer

 609 protective layer

 701 inkjet nozzles

 702 Inkjet nozzle unit

801 inkjet nozzles

802 Inkjet nozzle unit 803 Molded resin substrate

 901 Molded resin substrate

 902 First information recording layer

 903 Radiation curable resin

 904 Ink jet nozzle = =-

905 Irradiator

 906 Radiation means

 907, 908 シ タ タ

 1001 molded resin substrate

 1002 Information recording layer

 1003 Radiation curable resin

 1004 Transfer stamper

 1005 Center boss

 1006 pressure plate

 1007 Vacuum Channo

 1008 vacuum pump

 1009 Radiation device

 1101 Molded resin substrate

 1102 Application irradiated area

1103 Inkjet Nozzle: Knit

1104 Inkjet Nozzle: Knit

1201 Molded resin substrate

 1202 Outer wall surface

 1203 Inner edge wall surface

 1204 Radiation means

 1205 Inkjet Nozzle: Knit

1206 Radiation means

1207 Resin Intermediate Layer BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, an ink jet coating apparatus and a method of manufacturing a multilayer information recording medium according to an embodiment of the present invention will be described with reference to the attached drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

 Embodiment 1

 FIG. 6 is a cross-sectional view showing a structure of a multilayer information recording medium according to Embodiment 1 of the present invention. This multilayer information recording medium is a four-layer information recording medium which can be recorded and reproduced from one side. This four-layer information recording medium is configured by laminating four information recording layers on a molded resin substrate 601 on which an information surface of a guide groove having a concavo-convex shape is transferred and formed on one side. This multi-layer information recording medium comprises a first information recording layer 602, a first resin intermediate layer 603, a second information recording layer 604, and a second information recording layer formed in order on a molded resin substrate 601. And the third information recording layer 606, the third resin intermediate layer 607, the fourth information recording layer 608, and the protective layer 605. The first information recording layer 602 is disposed in contact with the first information surface formed on the molded resin substrate 601. The first resin intermediate layer 603 is laminated so as to be in contact with the first information recording layer 602, and has a second information surface on one side of which also has a concavo-convex shape force. The second information recording layer 604 is disposed in contact with the second information surface. The second resin intermediate layer 605 is laminated to be in contact with the second information recording layer 604, and has a third information surface having a concavo-convex shape on one surface. The third information recording layer 606 is disposed in contact with the third information surface. The third resin intermediate layer 607 is laminated so as to be in contact with the third information recording layer 606, and has a fourth information surface on one surface of which is also a concavo-convex shape force. The fourth information recording layer 608 is disposed in contact with the fourth information surface. A protective layer 609 is provided in contact with the fourth information recording layer 608.

 In this multilayer information recording medium, at least one resin intermediate layer of the first resin intermediate layer 603, the second resin intermediate layer 605, and the third resin intermediate layer 607 will be described later. It is characterized in that it is manufactured by applying a radiation curable resin and irradiating a radiation by an ink jet coating apparatus. For this reason, the end face of the resin intermediate layer has a zigzag shape depending on the size of droplets discharged from the ink jet nozzle.

Each component of the multilayer information recording medium will be described below. Molded resin substrate>

 The molded resin substrate 601 may be any one as long as it can support the information recording layer, resin intermediate layer, and protective layer laminated thereon. Note that, for example, a disc having an outer diameter of φ 120 mm, a central hole diameter of 15 mm, and a thickness of about 1.0 to 1.1 mm so as to be geometrically compatible with an optical disc such as a CD, DVD, or Blu-ray disc. It is preferable to have a shape. The molded resin substrate 601 is preferably formed of polycarbonate or acrylic resin. The molded resin substrate 601 is formed with an information surface such as a guide groove formed on one surface by concavo-convex formation by resin molding by injection molding or the like using the metal stamper shown in FIG. 3 (f). . In the first embodiment, polycarbonate is used.

<Step of Producing Metal Stamper for Producing Molded Resin Substrate>

 FIGS. 3 (a) to 3 (f) are schematic views showing steps of producing a stamper which is a metal mold for producing a molded resin substrate of an information recording medium.

 (a) First, a photosensitive material such as a photoresist is coated on a master disk 301 which can be a glass disk or a silicon wafer, etc. to form a photosensitive film 302.

 (b) Next, a pattern such as a pit or a guide groove is exposed using an exposure beam 303 such as a laser beam or an electron beam (FIG. 3 (a)). As a result, a latent image consisting of the exposure unit 304 is formed (FIG. 3 (b)).

 (c) Thereafter, the exposed portion 304 is removed with an alkaline developer or the like to obtain a recording master 306 having a concavo-convex pattern 305 formed of a photosensitive material on the master 301 (FIG. 3 (c)).

 (d) A conductive thin film 307 is formed on the surface of the recording master 306 by sputtering, evaporation or the like (FIG. 3 (d)).

 (e) A metal plate 308 is formed by metal plating or the like using the above-mentioned conductive thin film 307 as an electrode (FIG. 3 (e)).

 (f) Next, the conductive film 307 and the metal plate 308 are peeled off at the interface between the photosensitive film 302 and the conductive thin film 307. Further, the photosensitive material remaining on the surface of the conductive film 307 is removed by a removing material or the like. Thereafter, the metal stamper 309, which is a metal mold for molding of a molded resin substrate, is manufactured by performing punching forming to inner and outer diameters matched to a molding machine (FIG. 3 (f)).

<First Information Recording Layer> When the information recording medium is a read-only medium, the first information recording layer 602 may have at least a characteristic of reflecting the reproduced light. For example, Al, Ag, Au, Si, SiO, TiO etc.

 The reflective material is formed using a method such as sputtering or vapor deposition. In addition, when the information recording medium is a recordable medium, it is necessary to write the information by irradiating the recording light. For example, a layer having a recording material strength such as a phase change material such as GeSbTe or an organic dye such as phthalocyanine. May be included at least. Further, if necessary, a layer such as a reflective layer or an interface layer may be included to improve the recording and reproducing characteristics. The second information recording layer 604, the third information recording layer 606, and the fourth information recording layer 608 can be similarly formed. However, since recording and reproduction are performed by causing recording and reproduction light to enter the respective information recording layers on the side of the protective layer 609, recording and reproduction are sequentially performed from the first information recording layer to the fourth information recording layer. It is preferred to be configured to have high transmittance to the wavelength of light.

 <First Resin Intermediate Layer>

 The first resin intermediate layer 603 is a resin substantially transparent to recording and reproduction light, for example, an ultraviolet curable resin containing acrylic as a main component! In the above, it is possible to use a radiation curable resin such as an epoxy type ultraviolet curable resin. The term "substantially transparent" as used herein means having a transmittance of 90% or more with respect to the wavelength of recording / reproducing light, and a material having a transmittance of 95% or more is more preferable.

 [0048] The method for producing the first resin intermediate layer 603 is

 (a) applying a radiation curable resin onto the first information recording layer 602 using an ink jet coating apparatus described later and applying the radiation onto the first information recording layer 602;

(b) transferring the information surface to the surface of the radiation curable resin by using a transfer stamper having an information surface such as pits and guide grooves;

 including.

<Transfer Stamper>

 First, the transfer stamper 1004 will be described.

The transfer stamper 1004 uses a polyolefin material which is a material having good releasability from the radiation curable resin, and the thickness thereof is thinner than that of a molded resin substrate, for example, 0.6 mm. Are formed. The purpose of this is to make the transfer stamper warp and peel using the difference in rigidity due to the difference in thickness of the molded resin substrate having a thickness of about 1.1 mm when peeling the transfer stamper from the substrate. Because of The polyolefin material is a material capable of easily producing an information surface such as pits and guide grooves formed on one side by a method such as injection molding using a conventional metal stamper and the like like the molded resin substrate. In addition, since the polyolefin material has a high transmittance to radiation such as ultraviolet light, radiation irradiation through the transfer stamper can cure the radiation curable resin efficiently. Furthermore, the polyolefin material can be easily peeled off at the interface with the radiation curable resin after the adhesive is hardened when the adhesion with the cured radiation curable resin is reduced. At the center of the transfer stamper 1004, a center hole for eccentricity is provided via a molded resin substrate 1001 and a center boss 1005.

Transfer Process by Transfer Stamper

 FIGS. 10 (a) to 10 (d) are diagrams showing an example of the process of transferring the information surface to the resin interlayer according to the first embodiment of the present invention.

 (a) The formed resin substrate 1001 on which the application of the radiation curable resin 1003 is completed is conveyed into a vacuum chamber 1007. At this time, the transfer stamper 1004 is also disposed in the vacuum chamber 1007 (FIG. 10 (a)).

 (b) Vacuum chamber The inside of the chamber 1007 is evacuated by a vacuum pump 1008 such as a rotary pump or a turbo molecular pump to create a vacuum atmosphere.

 (c) When the pressure in the vacuum chamber 1007 reaches a degree of vacuum of 100 Pa or less, the transfer stamper 1004 is superimposed on the molded resin substrate 1001 (FIG. 10 (b)). At this time, a pressure plate 1006 installed on the upper side of the transfer stamper 1004 presses the transfer stamper 1004 and the information surface on the transfer stamper is transferred to the radiation curable resin 1003. Since the inside of the vacuum chamber is a vacuum atmosphere, it is possible to bond the radiation curable resin 1003 and the transfer stamper 1004 together without bubbles being mixed.

(d) Radiation is applied to the molded resin substrate 1001 and the transfer stamper 1004 bonded to each other through the transfer stamper 1004 by the radiation irradiating apparatus 1009 inside or after the vacuum chamber is removed (FIG. 10 (FIG. c)). (e) Thereafter, the interface force between the radiation curable resin and the transfer stamper also peels off the transfer stamper 1004 by driving a wedge or blowing compressed air between the transfer stamper 1004 and the molded resin substrate 1001. Figure 10 (d). Thus, the first resin intermediate layer to which the information surface has been transferred is formed.

 In addition to the above, as the transfer stamper 1004, a different material such as metal may be used, for example. Further, an intermediate resin layer consisting of two or more resin layers may be formed by using two or more types of radiation curable resins. Furthermore, radiation may be irradiated from the side of the molded resin substrate. There are various methods of transferring the information surface to the radiation curable resin, but the use of any method does not limit the effect of the present invention.

 The second resin intermediate layer 605 and the third resin intermediate layer 607 can also be produced by the same method as the first resin intermediate layer 603.

 <Protective Layer>

 The protective layer 609 is preferably substantially transparent to the recording and reproducing light. For example, UV curable resins mainly composed of acrylics, or radiation curable resins such as UV curable epoxy resins can be used. The term "substantially transparent" as used herein means having a transmittance of 90% or more to the wavelength of recording / reproducing light, and a material having a transmittance of 95% or more is more preferable.

As a method of forming the protective layer 609, various methods such as a spin coating method, a screen printing method, a gravure printing method, and an ink jet method can be considered. As a method for forming the protective layer 609, it is preferable if the same method as the above-mentioned process for producing the resin intermediate layer can be used. For example, when the resin intermediate layer is applied by the ink jet method, it is most preferable to use the ink jet method also for the formation of the protective layer. Further, the method of forming the protective layer is not limited to the method of applying a radiation curable resin, and for example, a polycarbonate resin, a sheet-like material that also has a force such as an acrylic resin, may be bonded via an adhesive. May form

<Thickness of Each Layer>

In addition, the multilayer information recording medium according to the first embodiment of the present invention uses a blue-violet laser with a laser beam of 405 nm, an objective lens with an NA of 0.85, and a protective layer 609 side information. The beam is narrowed to the recording layer to perform recording and reproduction. In order to reduce the influence of the disc tilt, the thickness from the surface of the protective layer 609 to the first information recording layer 602 is set to about 0.1 mm.

 The thickness of the protective layer 609 is preferably set to about 40 m or more in order to reduce the influence on the recording and reproduction characteristics of each information recording layer due to dust or the like attached to the surface of the protective layer. . In addition, it is more preferable to set to 50 m or more.

 In addition, the thicknesses of the first resin interlayer, the second resin interlayer, and the third resin interlayer may be different from each other in order to reduce the influence of crosstalk and interference from other layers. It is preferable to set. Here, each thickness was designed to be about 15 μm, about 20 m, and about 10 m. The thickness of the protective layer was set to about 55 m. However, the design value of the thickness of each resin intermediate layer is an example, and the effect of the present invention remains the same even with other thickness design values.

 As described above, the structure of the multilayer information recording medium according to the first embodiment of the present invention and the outline of the method for manufacturing the multilayer information recording medium are briefly described. It is characterized in the method of forming the protective layer. Therefore, the scope of the present invention is not limited by the other configurations or the manufacturing method thereof.

 <Method of Manufacturing Multilayer Information Recording Medium>

 A method of manufacturing a multilayer information recording medium using the ink jet coating apparatus according to the first embodiment of the present invention will be described. In particular, the method for producing the resin intermediate layer constituting the multilayer information recording medium will be described in detail.

 FIG. 1 is a schematic view showing a configuration of an ink jet coating apparatus according to Embodiment 1 of the present invention. FIG. 1 is a view showing an example of a coating and irradiation process including coating of a radiation curable resin using the inkjet coating device and curing by radiation irradiation. A resin intermediate layer is formed by this application and irradiation process.

 <Configuration of Inkjet Coating Apparatus>

As shown in FIG. 1, the inkjet coating apparatus includes an inkjet head 107 and a drive unit (not shown) for moving the inkjet head 107 relative to the application target in the direction of the arrow. The ink jet nozzle unit 104 and the radiation irradiating means 106 are fixed to the ink jet head 107 with the radiation shielding plate 105 interposed therebetween. First, each component of the ink jet head 107 will be described.

 The inkjet nozzle unit 104 is provided with at least one inkjet nozzle. As this inkjet nozzle, one used for a printing machine for printing or drawing may be used. The ink jet nozzle can discharge minute droplets of ink mainly composed of pigment, dye and the like. With this ink jet technology, development is in progress to generate droplets as small as possible, for example, droplets of about several pL, and drop the droplets with high accuracy to realize printing with higher resolution. 10 to 2 in the present invention while

Since it is necessary to form a relatively thick resin layer of about 0 m, it is preferable to use an ink jet nozzle capable of discharging a droplet as large as possible. For example, it is preferable to use an ink jet nozzle capable of discharging large droplets of about several tens pL. At present, ink jet nozzles for printing machines generally available generally have a volume of microdroplets of about 5 to 50 pL, a corresponding resin viscosity capable of discharging about 5 to 50 mPa's around the discharge part, and an operating frequency of 1 kHz. There is about 20 kHz.

 FIGS. 5 (a) and 5 (b) are cross-sectional views of a typical configuration example of the ink jet nozzle. In the figure, the supply path of the discharged liquid to be discharged, the liquid tank and the like are omitted. FIG. 5 (a) shows a type in which the ejection liquid 501 is ejected and ejected by a vibration element 502 such as a piezoelectric element, and is called a piezo inkjet nozzle. FIG. 5 (b) is a type in which the discharge liquid is instantaneously boiled using the heater 503 and discharge is performed using the volumetric expansion of the discharge liquid 504 in the vicinity of the heater as a power source, and is called a thermal method.

 Although an inkjet head using one inkjet nozzle has been described here, the present invention is not limited to this, and a plurality of inkjet nozzles may be provided. For example, as shown in FIG. 7A, a plurality of inkjet nozzles may be arranged in a line in the direction perpendicular to the scanning direction of the inkjet head, and an inkjet head array may be provided. Further, as shown in FIG. 7 (b), there is a method of arranging a plurality of lines in the scanning direction, or a method of arranging a plurality of lines while slightly shifting the positions of the nozzles as shown in FIG. 7 (c).

In the inkjet head 107 according to the first embodiment of the present invention, a direction perpendicular to the scanning direction can be applied so that a length of 120 mm, which is the diameter of the molded resin substrate 101 to be applied, can be applied at one time. At least one row, with a width of 120 mm or more A configuration that arranges linearly is desirable.

 Therefore, in the ink jet coating apparatus according to the first embodiment of the present invention, an ink jet nozzle with an ejection force force OpL of 1 droplet and a driving frequency of 7 kHz is used, as shown in FIG. 8, in the scanning direction at 70 / zm pitch. On the other hand, an ink jet nozzle, Nore unit 802, in which 1,800 ink jet nozzles 801 were arranged in a straight line in the vertical direction, was used. If the ink jet nozzle is a resin having a viscosity of about 5 to 50 mPa's, it is possible to stably eject 40 pL of one drop.

 Here, it is also possible to use an ink jet nozzle unit as shown in FIG. 11 (a), which uses an ink jet nozzle unit as shown in FIG. In this case, the ink jet head can be moved in a direction perpendicular to the scanning direction, and the entire surface can be coated by scanning the substrate several times. In this case, a mechanism for moving the inkjet head in the direction perpendicular to the scanning direction is required.

 As shown in FIG. 8 and FIG. 11 (b), the length in the direction perpendicular to the scanning direction of the molded resin substrate to be coated, ie, the ink jet nozzle having a length longer than the diameter of the substrate. It is preferable to use Thus, the resin can be applied to the entire surface of the substrate by one scan.

 Next, the radiation irradiating means 106 will be described.

 The radiation irradiating means 106 is composed of a radiation source and an optical path for guiding the radiation generated from the radiation source to the side of the molded resin substrate 101 which is an object to be coated. Here, an ultraviolet lamp is used as a radiation source. Furthermore, various lamps such as a metal halide lamp, a high pressure mercury lamp and a xenon lamp can be used as the ultraviolet lamp. Here, a xenon lamp is used. However, it is necessary to select the wavelength of radiation to be applied, etc. according to the radiation curable resin used for coating, and the types of radiation source and lamp to be used are not limited to the above examples.

 Further, as shown in FIG. 1, the radiation irradiating means 106 is fixed at the back of the scanning direction of the ink jet nozzle unit together with the ink jet nozzle unit 104 which scans the molded resin substrate 101 as the object to be coated. It is done. Radiation is sequentially applied to the applied radiation curable resin layer using the radiation irradiating means 106.

The radiation shielding plate 105 is configured so that the radiation irradiated by the radiation irradiating means 106 is an ink It prevents leakage to the nozzle 104 side. That is, the radiation shielding plate 105 can prevent irradiation of radiation emitted from the radiation irradiation unit before the droplets of the radiation curable resin discharged from the ink jet nozzle are applied.

 According to the above configuration, the radiation curable resin 109 is applied by the ink jet nozzle set 104 constituting the ink jet head 107. Next, radiation is sequentially applied to the applied radiation curable resin 109 by radiation irradiating means 106 disposed at a predetermined interval behind the ink jet nozzle unit 104. Of the applied radiation curable resin, the region 110 irradiated with radiation is cured to suppress the flow of the resin. The region 110 irradiated with the radiation may be completely cured, but if it is cured to a state equivalent thereto without being completely cured, the flow of the resin can be suppressed. The state according to complete curing as referred to herein means a gel-like state or a state having a viscosity of 100 OO mPa's or more.

 Next, the drive unit will be described.

 The drive unit moves the inkjet head 107 relative to the application target. Therefore, at least one of the application object and the inkjet head 107 may be moved by the drive unit. For example, the ink jet head 107 may be scanned linearly with respect to the molded resin substrate 101 which is the application object by the drive unit. Further, the inkjet head 107 may be scanned at a constant speed with respect to the molded resin substrate 101 by the drive unit. By scanning at a constant speed in this way, radiation can be irradiated after a predetermined time has elapsed after the application of the radiation curable resin. Since radiation is applied after a predetermined time after application, the flowable state of the radiation curable resin can be cured in substantially the same state. For example, it can be hardened after so-called leveling, in which droplets of the radiation curable resin become overlapped with adjacent droplets. This makes it possible to improve the uniformity of the resin intermediate layer thickness.

 Application of Radiation-Curable Resin Using an Inkjet Coating Apparatus and Irradiation of Radiation> The application of radiation-curable resin using the above-described ink jet application apparatus and irradiation of radiation will be described below.

(a) First, vacuum adsorption of the molded resin substrate 101 having the first information recording layer 102 formed on one side It fixes to stage 103 by. The fixing method is not limited to the vacuum adsorption method, and other fixing methods may be used. Above the molded resin substrate 101, an inkjet head 107 having an inkjet nozzle unit 104 and radiation irradiating means 106 is disposed. The inkjet nozzle unit 104 is composed of at least one or more inkjet nozzles. In addition, a driving unit (not shown) for moving the ink jet head 107 relative to the stage 103 to which the molded resin substrate 101 is fixed is provided. The inkjet head 107 and the drive unit constitute an inkjet coating apparatus.

 Although the case where the stage 103 is fixed and the inkjet head 107 is moved in parallel to perform coating is described here, the present invention is not limited thereto, and the stage 103 and the inkjet head 107 may be moved relative to each other. Conversely, the stage 103 may be moved in parallel or both may be moved.

 (b) While moving the inkjet head 107 in parallel with respect to the stage 103, the radiation curable resin 108 which has become minute droplets from the ink jet nozzle die 104 is dropped onto the resin substrate 101. Do. Subsequently, radiation is sequentially applied to the applied radiation curable resin layer by radiation irradiating means 106 disposed at a predetermined interval behind ink jet nozzle unit 104.

 By the above process, radiation curable resin can be applied and radiation can be irradiated.

<Conditions for Ink Jet Coating Apparatus>

 Next, each condition in this inkjet coating device is examined.

Using this inkjet head 107, application and radiation of three types of radiation curable resins with different viscosities were performed. In this case, the scanning speed for the molded resin substrate of the ink jet head is fixed at 0.5 mZs, and the distance between the ink jet nozzle unit and the radiation irradiating means is 20 mn! The application was performed by setting to 150 mm. The radiation was irradiated with ultraviolet light at a setting of about 200 miZcm ² . The results are shown in Table 1 below. The resin does not cure completely at the above-mentioned irradiation intensity of radiation. However, the flow of resin itself can be suppressed to a certain extent.

Under the respective conditions, the average value of the thickness of the resin layer after application and the thickness variation in the surface Also, the extent to which the resin spreads out at the inner edge or the outer edge of the coated area was also confirmed. In addition, as dispersion | variation in application | coating thickness, +/- 2 m was provided as a reference value of the pass / fail judgment.

Also, the radiation curable resin is applied from the inkjet nozzle unit of the inkjet head, and the time until the radiation curable resin applied is sequentially irradiated with radiation from the radiation irradiating means of the inkjet head is applied. Calculated. The "time between application and irradiation" was calculated as "the distance between the nozzle and the radiation irradiating means" divided by the "scanning speed".

[Table 1]

According to the results in Table 1, in case of resin A having a resin viscosity of 5 mPa's, when the distance between the ink jet nozzle and the radiation irradiating means is 150 mm, the resin applied to both the inner edge and the outer edge of the coated area protrudes I confirmed that. Also, ink jet nozzles and radiation Under the condition of 120 mm or less, there was no problem with thickness variation and resin protrusion.

 For resin B having a resin viscosity of 20 mPa · s, under conditions where the distance between the ink jet nozzle unit and the irradiation means is 120 mm or less, in-plane thickness variation and resin protrusion within a reference value are also confirmed. It was When the distance between the ink jet nozzle unit and the radiation irradiating means was 150 mm, the thickness variation exceeded the reference value, and it was confirmed that a part of the resin was protruding at the outer edge of the coated area.

 In the case of resin C having a resin viscosity of 50 mPa · s, neither thickness variation nor resin protrusion was confirmed within the reference value under the condition that the distance between the ink jet nozzle unit and the irradiation means was 120 mm or less. When the distance between the ink jet nozzle unit and the radiation irradiating means was 150 mm, the force that resin protrusion was confirmed at a part of the outer periphery was hardly a problem in other cases.

 From the above results, in the resin viscosity range of 5 mPa's to 50 mPa's that can be discharged by the ink jet nozzle, setting the distance between the ink jet nozzle unit and the radiation irradiating unit to 120 mm or less makes uniform. It was confirmed that the resin layer could be applied. Further, it is desirable to set the distance between the ink jet nozzle unit and the radiation irradiating means to 50 mm or less because the quality is further improved.

 Regarding the distance between the ink jet nozzle unit and the radiation irradiating means>

 This inkjet coating apparatus is characterized in that the inkjet nozzle unit and the radiation irradiating means are disposed apart from each other at a predetermined interval in the inkjet head. That is, after the radiation curable resin is applied, it can be cured by irradiation with radiation sequentially. In this case, the droplets of the radiation curable resin that has been applied flow and overlap with the adjacent droplets, and after so-called leveling occurs, the droplets further flow and spread. After that, the thickness gradually decreases. In this inkjet coating apparatus, after coating, after the droplets are leveled, radiation is sequentially applied for curing. For this reason, the time from the application of the radiation curable resin to the irradiation of the radiation becomes important.

 Then, “time to irradiation after application” is examined.

(a) First of all, the lower end of the ink jet nozzle and the surface of the molded resin substrate to be coated are The working distance WD (m) and the discharge speed of radiation curable resin V (m / s). The working distance WD (m) is approximately

0. 001 (m) WD WD ≤ 0. 01 (m)

It becomes. In addition, when the viscosity V of the radiation curable resin V (mZs) is in the range of 5 to 50 (111? _& '3)

1 (m / s) ≤ V ≤ 6 (m / s)

It becomes.

 (b) By the working distance WD and the discharge speed V,

Ti = WD / V (s)

It is the time until the Ti (s) discharges the radiation curable resin and adheres to the object to be coated. Furthermore, using the above working distance WD and discharge speed V ranges

, Time to adhesion Ti,

 0. 00017 (s) ≤ Ti ≤ 0. 01 (s)

It becomes.

 (c) Next, with regard to the time T1 until the radiation curable resin flows and leveling, it varies depending on the physical properties of the radiation curable resin, but it becomes about 0. 01 (s) or so.

 (d) In order to cure by irradiation with radiation after leveling of the radiation curable resin, 0. 01007 (s) ≤ Ti + Tl ≤ 0.2 (s)

It becomes.

 (d) Therefore, after application of the radiation curable resin, the time until irradiation occurs is the time until leveling occurs:

 0. 01 (s) ≤ (Time to irradiation after application) ≤ 0. 02 (s)

It can be estimated. That is, the lower limit value of "time to irradiation after application" can be estimated to be approximately 0. Olsec.

 Furthermore, as to the upper limit value of "time to application and irradiation", it can be seen that, according to Table 1, it is acceptable up to about 0.24 sec. Therefore, the upper limit value of "time to irradiation after application" can be estimated to be 0.25 sec from the result of the example.

From the above results, the "time until application after application" is in the range of 0.1 sec to 0.25 sec. preferable.

 <Scanning Speed of Ink Jet Head to Molded Resin Substrate>

 From the above results, it was found that the formation of a uniform resin layer was possible, but the thickness of the resin intermediate layer in Embodiment 1 of the present invention should be in the range of 10 m to 20 m. There is no need to apply so as to make the coating thickness thicker. Therefore, when the distance between the ink jet nozzle and the radiation irradiating means is set to 50 mm using resin B having a resin viscosity of 20 mPa's, the scanning speed of the ink jet head with respect to the molded resin substrate is changed. The results are shown in Table 2 below. Table 2 shows the change in coating thickness, thickness variation, swelling of resin, and time to irradiation after coating.

 [Table 2]

As the scanning speed of the inkjet head with respect to the molded resin substrate is reduced, the dropped microdroplets are applied onto the molded resin substrate in an overlapping manner. In addition, the total amount of the dropped resin is inversely proportional to the scanning speed. From the results in Table 2, it was also confirmed that the coating thickness increased in inverse proportion to the scanning speed. In addition, I was not able to see the entrapment of air bubbles in particular.

As described above, by appropriately changing the scanning speed of the ink jet head with respect to the molded resin substrate without changing the configuration of the ink jet head, it is possible to control the thickness to some extent. Therefore, according to the thickness design of the first resin middle layer, the second resin middle layer, and the third resin middle layer, the desired resin middle layer thickness can be obtained by finely adjusting this scanning speed. Can be realized. Further, since the transfer process of the information surface of the transfer stamper is continued after the application of the radiation curable resin by the ink jet coating apparatus, the radiation dose at the time of application of the radiation curable resin is completely determined. It is necessary to use a smaller dose than the curing dose. Here, the irradiance of the radiation irradiating means was about 200 mj Zcm ² . Under these conditions, it was confirmed that light and tackiness remained on the surface of the radiation curable resin layer after application. Further, when groove transfer is performed using the transfer process of the information surface of the transfer stamper described with reference to FIGS. 10A to 10D, the transfer is performed with respect to the groove depth of the original transfer stamper. The groove depth of the radiation curable resin layer was about 97%. This value is sufficient for transferability.

 <Another Example of Configuration of Ink Jet Coating Apparatus>

 Next, another configuration example of the ink jet application apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 9 (a) and 9 (b). FIGS. 9 (a) and 9 (b) are schematic views showing the configuration of an ink jet head having radiation irradiating means on the front side and the rear side of the relative movement direction of the ink jet head with respect to the object to be coated. The ink jet nozzle unit may have the same configuration as that shown in FIG. By using the ink jet head, a thickness of 10 m to 20 m can be realized by performing multiple coats.

 As shown in FIGS. 9 (a) and 9 (b), this inkjet head emits radiation to each of the front and rear sides with respect to the scanning direction of the inkjet nozzle seat 904 and the inkjet nozzle unit. Irradiation means 906 is provided. In the radiation irradiating means 906, the route for guiding the radiation emitted from the radiation lamp 905, which is a light source, to the side of the molded resin substrate 901 is branched into two, and arranged in front and back with respect to the scanning direction of the ink jet nozzle unit. In addition, the shutters 907 and 908 are provided at the two injection ports of the radiation irradiating means 906 respectively. According to this ink jet head, since the radiation irradiating means is disposed before and after the ink jet nozzle unit, it is not necessary to rotate the ink jet head itself when reversing the scanning direction when scanning linearly. .

First, when the first application is performed (FIG. 9 (a)), the shutter 907 of the radiation irradiating means on the front side in the direction of movement of the ink jet nozzle unit is closed, and the shutter 908 on the rear side is opened. Only the radiation irradiating means on the back side with respect to the scanning direction of the inkjet Keep it. Thus, after the first coating and irradiation process, the ink jet head scans the molded resin substrate in the opposite direction to the above (Fig. 9 (b)). At this time, the radiation irradiating means closes the shutter 908 on the front side with respect to the scanning direction and opens the shirt 907 on the rear side to make only the radiation irradiating means on the rear side with respect to the scanning direction of the ink jet nozzle effective. deep. By repeating this operation, it is possible to coat several times.

 Table 3 shows the results of coating thickness when resin B having a resin viscosity of 20 mPa's is used and the distance between the ink jet nozzle unit and the radiation irradiating means disposed before and after it is set to 50 mm.

 [Table 3]

From the results in Table 3, it was confirmed that the coating thickness was thick enough to be applied approximately in proportion to the number of layers stacked. In addition, the bubbles were especially absorbed, and the resin was pushed out at the inner and outer edges of the application area. In addition, thickness distribution tends to increase as the number of scans increases because coating is repeated. However, if the coating is performed under these conditions, coating to a thickness of about 8 m to 23 μm can be realized without any problem.

 In this case, the experiment was carried out with a radiation dose of 200 mj Zcm 2 constant for all scans in this case, but considering the groove transfer process after application of the resin layer, it is possible to repeat this process several times. When the coating and irradiation steps are repeated, the radiation dose in at least the final coating and irradiation steps may be adjusted to ensure that the radiation curable resin does not completely cure.

[0098] For example, when scanning 3 times, in the first and second coating and irradiation steps, radiation was set to LOOOmiZcm ^2, to cure the almost completely radiation-curable榭脂. Meanwhile, the last In the third coating and irradiation step, there is a method of facilitating the groove transfer without completely curing the radiation curable resin with an irradiation amount of 200 mj and Z cm ² . Moreover, it is easy to increase / decrease this radiation exposure amount by the aperture ratio of the shirt provided at the radiation exit.

Also, for example, in the case of performing three coating operations and three application processes and irradiation processes, in the first and second application and irradiation processes, the radiation is set as lOOOiuJ / m ² and the radiation hardening is almost completely performed. The curable resin is allowed to cure. On the other hand, in the third application and irradiation step, the irradiation amount of Omj / cm ² , that is, radiation may not be applied. In this case, groove transfer can be facilitated because the outermost surface of the radiation curable resin remains uncured. Also in this case, the same effect as the method described above can be obtained.

 Also, it is possible to carry out a plurality of coating and irradiation steps to apply a plurality of types of resin! For example, there is a molded resin substrate! The film is better than the first information recording layer Overcoating was performed with resin E having adhesiveness and resin F having good releasability with respect to the transfer stamper. This layer configuration is preferable because it facilitates the subsequent groove transfer process. The application results in this case are shown in Table 4.

[0101] [Table 4]

From the above results, it was confirmed that even if two types of resins were used as the radiation curable resin, the thickness was increased in proportion to the number of times of coating. In the last coating and irradiation steps of the coating and irradiation steps, the radiation amount may not be completely cured but may be dropped to the irradiation amount. It is preferable to set the state in which the film is not completely cured as described above, since the groove transferability after that becomes good. Also, application of resin F The same effect can be obtained by setting the radiation dose to 0 mi / _C m ² , that is, without radiation, in the radiation process.

 Furthermore, although the process for producing the first resin intermediate layer has been described here, the present invention is not limited to this, and it may be used for the process for producing the second resin intermediate layer and the third resin intermediate layer. Good. Also in this case, the effect of the present invention is effective, and has an effect in the preparation steps of all the resin intermediate layers.

 Second Embodiment

 The process for producing the resin intermediate layer in the method for producing a multilayer information recording medium according to the second embodiment of the present invention will be described with reference to FIGS. 12 (a) to 12 (c). Compared to the method of manufacturing the multilayer information recording medium according to the first embodiment, the method of manufacturing the multilayer information recording medium includes the steps of manufacturing the resin intermediate layer,

 (a) forming a wall portion of a radiation curable resin on an inner peripheral portion and an outer peripheral portion surrounding a region for forming a resin intermediate layer;

 (b) applying a radiation curable resin to a region surrounded by the inner peripheral portion and the wall portion of the outer peripheral portion, and applying and irradiating the radiation sequentially after the application;

 It is characterized by including.

The remaining steps other than the application of the resin intermediate layer and the irradiation step are substantially the same as the steps described in the first embodiment, and therefore the description thereof is omitted here. Further, the effect of the present invention is due to the process of producing the resin intermediate layer, and the other processes do not narrow the effects of the present invention regardless of the process.

FIGS. 12 (a) to 12 (c) show a method for producing a resin intermediate layer according to Embodiment 2 of the present invention. The configuration of the ink jet head was the same as that shown in FIGS. 9 (a) and 9 (b) of the first embodiment.

(a) A step of applying and irradiating a radiation curable resin to a portion surrounding the inner and outer peripheral portions of the application region of the resin intermediate layer formed on the molded resin substrate 1201 in a ring shape using the above-mentioned ink jet head Do (Figure 12 (a)). The configuration of the ring-shaped wall surfaces 1202 and 1203 can be realized by a force for adjusting the scanning speed of the ink jet head or by performing coating multiple times so as to obtain a desired thickness in the application region. Using the configuration of the inkjet head according to the first embodiment of the present invention, curing before resin flow occurs. It is possible to make wall surfaces of uniform thickness.

 (b) Thereafter, a radioactive curable resin is discharged to a region surrounded by the wall surface 1202 of the outer peripheral portion and the wall surface 1203 of the inner peripheral portion, and a resin intermediate layer having a uniform thickness corresponding to the height of the wall surface is formed. it can.

 Table 5 shows the thickness measurement results of the resin intermediate layer formed by this method.

[0107] [Table 5]

The resin was applied twice by scanning at a scanning speed of 0.5 mZs using a resin having a viscosity of 20 mPa's. The width of the wall is about 200 μm and the thickness is about 15 m. The irradiation of radiation was performed in lOOOmiZcm ^2. In addition, the resin was applied to the entire application area at a third scan speed of 0.3 mZs. No radiation was irradiated in the third resin application.

 In general, when a resin having a resin viscosity of 20 mPa's is applied to a thickness of 15 m, swelling of the outer peripheral end surface occurs when the resin flows, so that a large variation appears in the in-plane thickness distribution. . However, in the second embodiment, as shown in Table 5, even when radiation was not applied, the result of a good thickness distribution with a variation of ± 1.5 m was obtained.

Here, the experiment was conducted only with a resin having a viscosity of 20 mPa's. As described in the first embodiment, the coating thickness can be controlled within the viscosity range which can be discharged by the ink jet nozzle.

The same applies to the second embodiment of the present invention.

Further, although only the preparation of the first resin intermediate layer is mentioned here, the present invention is also effective in the process of forming other resin intermediate layers. It can also be used in the step of forming a protective layer. Industrial applicability

 The ink jet coating apparatus of the present invention is useful as a method of forming multilayer media such as multilayer information recording media. In particular, it can be used in the process of laminating resin layers such as Blu-ray discs.

Claims

The scope of the claims

 [1] While relatively moving either one of the application object or the inkjet head

An inkjet coating device for applying a radiation curable resin to the application object, the inkjet unit having an inkjet nozzle for discharging droplets of the radiation curable resin, and the application object of the inkjet unit An inkjet head comprising: a radiation irradiating unit provided behind the relative moving direction at a predetermined interval and irradiating the radiation curable resin applied to the application object with radiation; And a driving unit for moving the ink jet head relatively.

 [2] The drive unit moves the inkjet head relative to the application target at a constant speed,

 The radiation is applied to the radiation curable resin applied from the ink jet nozzle to the object to be coated in a given time after application, and the radiation is sequentially irradiated.

[3] The inkjet coating device according to claim 2, wherein the drive unit moves the inkjet head relative to the application object in a linear direction.

[4] The ink jet head is held between the ink jet nozzle unit and the radiation irradiation unit.

 The radiation shielding plate may further include a radiation shielding plate for preventing irradiation of radiation emitted from the radiation irradiation unit before the droplets of the radiation curable resin discharged from the ink jet nozzle are applied. The inkjet coating device according to claim 1.

[5] The ink jet head includes a first radiation irradiating unit and a second radiation arranged at predetermined intervals from the ink jet unit at the front and the back of the relative movement direction with the ink jet unit interposed therebetween. The inkjet coating device according to claim 1, comprising: an irradiation unit.

[6] The drive unit is connected to the application object. The ink jet head is moved back and forth in a straight line direction to move relative to each other. The inkjet head according to claim 5, wherein when the relative movement direction is reversed, the first radiation irradiation unit is switched to the second radiation irradiation unit to emit radiation. Coating device.

 [7] The inkjet head is characterized in that a plurality of inkjet nozzles are disposed in the inkjet nozzle unit in a direction perpendicular to the relative movement direction and over the width of the object to be coated. The inkjet coating device according to claim 1.

 [8] A substrate, a plurality of information recording layers disposed on the substrate, a resin intermediate layer disposed between the information recording layers, and a protective layer provided on the information recording layer A method of manufacturing a multilayer information recording medium, comprising:

 An ink jet unit having an ink jet nozzle for discharging droplets of a radiation curable resin, and an ink jet unit provided at a predetermined interval behind the relative moving direction of the ink jet unit with respect to the object to be coated, A radiation irradiation unit for irradiating the radiation curable resin applied to the object with radiation, and an ink jet application apparatus having an ink jet head including the ink jet head, wherein the ink jet unit is moved relative to the object to be coated to A radiation curable resin is dropped onto the object to be coated, and then the radiation curable resin is sequentially irradiated with radiation from a radiation irradiation unit to form a resin intermediate layer on the object to be coated. Coating and irradiation process of curable resin

 A method of manufacturing a multilayer information recording medium, comprising:

 [9] The object to be coated in the coating and irradiation steps is a substrate provided with an information recording layer,

 9. The method according to claim 8, further comprising a transfer step of forming an information surface on the surface of the radiation curable resin formed on the substrate by transfer.

 [10] The application target in the application and irradiation steps is a transfer stamper, and the step of overlaying the transfer stamper and the substrate by sandwiching the radiation curable resin, and overlaying the substrate;

The method according to claim 8, further comprising: a peeling step of peeling the transfer stamper from the radiation curable resin.

[11] The application and irradiation steps are

 A radiation curable resin is dropped onto the radially inner inner edge and the radially outer outer edge, and the radiation curable resin is then irradiated with radiation to have a predetermined coating thickness. Forming wall surfaces of an inner edge portion and an outer edge portion surrounding a region forming the resin intermediate layer made of resin;

 A step of applying a radiation curable resin to the region surrounded by the wall surface of the inner edge portion and the outer edge portion and thereafter irradiating the radiation curable resin with radiation to form a resin intermediate layer;

 A method of manufacturing a multilayer information recording medium according to claim 8, comprising:

[12] In the applying and irradiating steps, the ink jet coating apparatus is moved relative to the object to be applied at a constant speed, and radiation is applied after a predetermined time has elapsed after the application of the radiation curable resin. The manufacturing method of the multilayer information recording medium of Claim 8 characterized by the above-mentioned.

 [13] The method for producing a multilayer information recording medium according to claim 8, wherein the application and irradiation steps are performed a plurality of times.

[14] The irradiation dose of the radiation in the last step of the plurality of application and irradiation steps

The method for producing a multilayer information recording medium according to claim 13, wherein 1S is smaller than the irradiation amount in the coating and irradiation steps up to that time.

[15] The method for producing a multilayer information recording medium according to claim 13, wherein in the final step of the plurality of application and irradiation steps, only the radiation curable resin is applied.

 [16] The method for producing a multilayer information recording medium according to claim 11, wherein a plurality of types of resins are used as the radiation curable resin in the coating and irradiation steps.

[17] A method of producing the multilayer information recording medium according to any one of claims 8 to 16 is used.

A multilayer information recording medium characterized by being produced by V-stabilization.

[18] The multilayer information recording medium according to claim 17, wherein in the multilayer information recording medium, an end face of the resin intermediate layer exhibits a zigzag shape by droplets from the ink jet nozzle.